I tested them with a noid light and then whith a mutlimeter set for 12 volts. I replaced the fuel injector relay, the other device that is on the driverside inner fender by the brake booster, the wiring harness and the ECU. Whats left, am I missing something. The only thing that is not connected is the Temp sensor (the one wire one for the Gauge). The car starts but will die if I unplugged the cold start valve.

my old harness was only dead on cylinder #3 This one is dead on all!

Does anyone know where I can buy a brand new harness?

Do you have the Fuel Injection Bible? You can download it under members\downloads on this forum. What year is your Z? Have you checked all of the fusible links? You have to be careful not to replace too much all at once, especially when debugging the EFI because you could compound your problems.

Use the Fuel Injection Bible to help you inspect each component at a time, specifically there is a section where you check the continuity of the wiring harness between the ECU and a given component.

Do you have an FSM? This will help you in a much more general way -make sure that you have one for reference.

Do you have the Fuel Injection Bible? You can download it under members\downloads on this forum. What year is your Z? Have you checked all of the fusible links? You have to be careful not to replace too much all at once, especially when debugging the EFI because you could compound your problems.

Use the Fuel Injection Bible to help you inspect each component at a time, specifically there is a section where you check the continuity of the wiring harness between the ECU and a given component.

Do you have an FSM? This will help you in a much more general way -make sure that you have one for reference.

Thank you for your reply!

Yes I have the fuel injection bible. my car is a 78. I am only aware of the 4 fuseble links located near the battery and they are all good.

I am not sure what an FSM is?

FSM = Factory Service Manual

It's available also at www.xenons30.com. You'll find complete debugging procedures and data there.

Possible problems might include:

-- no power to ECU

-- no signal from ignition coil's (-) terminal to ECU's #1 terminal

-- bad drop resistor assembly (or connections). The drop resistors are located beneath the brake and clutch masters.

It's probably easier -- or at least much cheaper -- to repair your harness than to buy a new one. I don't even know whether new ones are available. You can buy new Bosch-style 2-conductor connectors here:

http://cgi.ebay.com/ebaymotors/injector-connector-kit-6pc-datsun-280z-280zx-300zx-/290452375892?pt=Motors_Car_Truck_Parts_Accessories&hash=item43a04f8954

(vender's name is f0rrest). You'll need 10 of them. There are a few other connectors, but that's most of them. The wires themselves will probably be fine.

my car is a 78. I am only aware of the 4 fuseble links located near the battery

There should be two fusible links more that are fed directly from the battery positive post. They are the the ones that supply power to your injectors and ECU. They're green.

Thanks for the input, I am heading out to the shop this morning to see what I can find! i guess I will refurbish my original harness.

FIXED, Holy moly! She has been down for at least 5 years with these issues.

Turns out #10 pin was dead as a door nail. I traced the wires up into the harness and found one that had deteriorated inside. I replaced it and BAM, she purrs like a kitten!

My injectors and cold start injector are leaking I'm guessing. During my tests the car kept starting with the ecm disconnected. No big deal, I will buy them new if the car is actually fixed.

Thanks for the input and I am excited to be moving in the direction of driving my Z again.

AR280z: Just so you'll have it - Follow this link and you can download my FSM for the 78 Z.

http://www.mediafire.com/?y2x2e66oh939z9t